In front of Esther Oluwagbenga sits an egg perched on a blue tripod. A tiny triangular window has been cut into the shell. When Dr. Oluwagbenga positions the hole under a microscope, she reveals the chick embryo inside.

In its third day of existence, the embryo has developed into a diffuse cloud, with a pinhead-size heart beating at its core. Cells course through crimson arteries in fits and starts, like rush-hour traffic.

Continue reading “How to Turn a Chicken Egg Into a Drug Factory” →

The Covid pandemic was an extraordinary moment in history. Starting at the end of 2019, a virus new to science swept across the planet, killed more than 25 million people and caused trillions of dollars in economic damage.

But as outbreaks go, Covid was pretty ordinary, a new study finds.

Scientists compared seven viral outbreaks that occurred in recent decades, including epidemics of Covid, Ebola and influenza. For the most part, the researchers found, the outbreaks were not preceded by any unusual genetic changes in the viruses. In all but one case, in 1977, the viruses circulated in animals and gained the ability to spread to and among people only by unfortunate coincidence.

Continue reading “Scientists Get a Glimpse of How New Pandemics Are Made” →

One of the biggest discoveries about human evolution in recent decades is that, tens of thousands of years ago, Neanderthals and modern humans interbred. As a result, most people alive today carry a bit of Neanderthal DNA in their genome — and that residual DNA, in turn, is giving scientists a detailed look at the ancient sexual encounters that put it there.

Continue reading “What Your DNA Reveals About the Sex Life of Neanderthals” →

Look at just about any vertebrate and you’ll see two eyes looking back at you. Falcons circling overhead have two eyes, just like hammerhead sharks roving through the ocean.

Scientists have long puzzled over how the vertebrate eye first evolved. A pair of new studies suggest a strange beginning: Our invertebrate ancestors 560 million years ago were cyclopes, with a single eye at the top of their head, scientists now propose, that only later split in two.

Continue reading “The Rise of Eyes Began With Just One” →

A flurry of new studies is shedding light on one of the biggest steps in the history of life: the evolution two billion years ago of complex cells from simpler ones. In the oceans and on land, scientists are discovering rare, transitional microbes that bridge the gap.

The differences between complex cells, including those in the human body, and simple microbes such as E. coli are stark. Complex cells are packed with compartments; one, known as the nucleus, stores DNA; others, called mitochondria, contain enzymes that generate the cell’s fuel supply. Complex cells are also supported internally by a mesh of filaments, that they use to crawl by breaking down parts of it and building new extensions.

Continue reading “How Microbes Got Their Crawl” →